Caption: Coriander stem. Light micrograph of a section through the stem of a coriander (Coriandrum sativum) plant, showing (from the outer stem to the centre: epidermis with cuticle (dark-blue); oval patches of collenchyma (dark-blue) and a cortex of parenchyma cells (light-blue); ring of separate vascular bundles made up of outer phloem fibres (dark blue); crescent-shaped phloem (blue) vessels; thin layer of cambium (blue); xylem vessels (dark-blue vessels). Between the vascular bundles are radial files of parenchyma cells called medullary rays. At the centre of the stem is the pith of large parenchyma cells (blue). Magnification: x13, when printed 10 centimetres wide.